Method and device for adjusting the liquid content of a solid withdrawn from a self-discharging centrifugal drum of a separator

ABSTRACT

The invention is a method and apparatus for adjusting a liquid content of a liquid and solid mixture withdrawn from a self-discharging centrifugal drum of a separator. The method includes the steps of: feeding a solid and liquid mixture into the separator; rotating the drum; separating the liquid and solid mixture during the rotation; bringing the separator to a halt; aspirating the liquid remaining in the interior of the centrifugal drum until a quantity remains which corresponds to a required consistency of a solid; and emptying the centrifugal drum of the solid with the required consistency from the centrifugal drum at a suitable rotational speed. The apparatus is a separator including: a self-discharging centrifugal drum; withdrawal openings; a solid space and a separating space; a feeding tube; a shutoff element; and a piston-type slide valve. A connection piece for the connection of a suction device is arranged below the shut-off element.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a method and a device for adjusting the liquidcontent of a solid withdrawn from a self-discharging centrifugal drum ofa separator, and to a device for implementing this method.

In the case of several products, it is desirable that the solidwithdrawn from self-discharging centrifugal drums has a content of drysubstance which is as large as possible. It is therefore preferred toprevent liquid from being ejected from the drum along with the solid. Inorder to achieve this, a so-called “partial discharge” is applied inwhich the centrifugal drum is opened only for such a short time that themajority of solids can escape.

In the case of other products, it is desirable to eject the solid with aliquid content which determines the endeavored consistency.

This cannot be achieved by means of the known separators and theirmethod of operation.

It is an object of the invention to design a method and a device of theinitially mentioned type such that, prior to the withdrawal of the solidfrom the centrifugal drum, the liquid content can be adjusted whichdetermines the consistency.

According to the invention, when the separator is brought to a haltafter separation, the liquid remaining in the interior of thecentrifugal drum is aspirated until a quantity remains which correspondsto the required consistency of the solid. Subsequently the centrifugaldrum is emptied at a suitable rotational speed, and then the solid iswithdrawn from the centrifugal drum.

For the aspiration of a portion of the liquid from the interior of thecentrifugal drum, the feeding tube feeds the solid/liquid mixture to thecentrifugal drum and which can be adjusted with respect to its heightand, in the lower end position, extends into the proximity of the drumbottom.

When the centrifugal drum is stopped, an inward and downward sloped drumbottom guides the residual fluid toward the interior and collects in thearea of the lower end of the centrally arranged feeding tube.

Because of the axial displaceability of the feeding tube, the free endcan be moved to the lowest point of the drum bottom, so that the liquidcan also be almost completely aspirated through the feeding tube whenthe inflow is shut off. Furthermore, by way of the adjusted distance ofthe lower opening of the feeding tube from the drum bottom, a remainingfluid quantity can be adjusted and the consistency of the withdrawnsolid can be influenced.

By using the feeding tube as a suction tube when the inflow of thesolid/liquid mixture is switched off, a simple construction is obtainedfor carrying out the suction operation in order to withdraw a desiredliquid quantity from the interior of the centrifugal drum.

The temporary use of the feeding tube as a suction tube is possible inthe case of stationary as well as co-rotating feeding tubes.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detail description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing is a schematic vertical sectional view of a centrifugal drumof a separator according to the principles of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The centrifugal drum 1 is composed of the bottom part 2, the top part 3and a connection ring 4. In the bottom part 2, a piston-type slide valve5 is slidably disposed and, in the indicated operating position, closesthe withdrawal openings 6 arranged in a distributed manner on thecircumference for the solid which, during the operation of theseparator, collects in the solid space 7.

The centrifugal drum 1 also has a separating space 8 in which a platestack is arranged.

The feeding of the solid/liquid mixture takes place through a feedingtube 9 which can be shut off in the upper area by means of a shut-offelement 10.

Below the shut-off element 10, a connection piece 11 branches off thefeeding tube 9, in which connection piece 11 and a shut-off valve 12 arearranged and connected with a suction device 22.

The feeding tube 9 can be adjusted in the axial direction, specificallyby means of an adjusting device 13 which is only outlined in thedrawing.

The bottom of the centrifugal drum is composed of a ring surface 14 ofthe piston-type slide valve 5 and of a ring surface 15 of the bottompart 2. The illustration shows that the surfaces 14 and 15 extend inwardand downward toward the center 16 and thus at a gradient, so that, whenthe centrifugal drum is stopped, the remaining fluid collects in thecentral lower area of the centrifugal drum. The distance of the loweropening 17 of the feeding tube 9, which is temporarily used as a suctiontube, can be precisely adjusted so that, as a result, the liquidquantity is determined which remains in the centrifugal drum and, afterthe restarting of the separator 20, when the withdrawal openings 6 areopened up, the determined liquid quantity is withdrawn together with thesolid.

Generally, after feeding a solid/liquid mixture through feeding tube 9and running the separator 20, the method of operation of the centrifugaldrum 1 comprises the following steps for adjusting a liquid content of aliquid and solid mixture withdrawn from the self-discharging centrifugaldrum 1 of separator 20: the separator 20 is brought to a halt; theliquid remaining in the interior of the centrifugal drum 1 is aspirateduntil a quantity remains which corresponds to a required consistency;and then, the centrifugal drum 1 is emptied at a suitable rotationalspeed.

When the centrifugal drum 1 is stopped, an inward and downward slopeddrum bottom 2 guides residue fluid (not shown) toward the interior andit collects in an area of the lower end of the centrally arrangedfeeding tube 9. The feeding tube 9 can be axially displaced by use of anadjusting device 13 and a free end can be moved to the lowest point ofthe drum bottom 2 so that the liquid can be almost completely aspiratedthrough the feeding tube 9 when the inflow of material is shut off byshut-off element 10. By adjusting the distance of the lower opening 17of the feeding tube 9 from the drum bottom 2, a remaining fluid quantitycan be adjusted and the consistency of the withdrawn solid can beinfluenced. That can be accomplished because the feeding tube 9 is usedas a section tube when the inflow of the solid/liquid mixture isswitched off at element 10. A connection piece 11 branches off fromfeeding tube 9 and connects to a suction device 22 via shut off valve12. This suction arrangement carries out a suction operation in order towithdraw a desired liquid quantity from the interior of the centrifugaldrum 1.

Although the present invention has been described and illustrated indetail, it is to be clearly understood that the same is by way ofillustration and example only, and is not to be taken by way oflimitation. The spirit and scope of the present invention are to belimited only by the terms of the appended claims.

What is claimed is:
 1. A method for adjusting a liquid content of aliquid and solid mixture withdrawn from a self-discharging centrifugaldrum of a separator, comprising the steps of: feeding a solid and liquidmixture into the separator; rotating the drum to separate the liquid andsolid mixture; bringing the separator to a halt, aspirating the liquidremaining in the interior of the centrifugal drum until a quantityremains which corresponds to a required consistency of a solid, andemptying the solid with the required consistency from the centrifugaldrum at a suitable rotational speed.
 2. The method according to claim 1,wherein the aspirating step includes using a feeding tube for feedingthe mixture to the centrifugal drum and wherein, the feeding tube can beaxially adjusted to a lower end position extending to an area near abottom of the drum.
 3. A separator for adjusting the liquid content of aliquid and solid mixture withdrawn from a centrifugal drum, theseparator comprising: a self-discharging centrifugal drum; withdrawalopenings configured on the centrifugal drum having a solid space and aseparating space equipped with a plate stack, as well as a feeding tubefor feeding a liquid and solid mixture, a shutoff element for closingoff an upper area of the feeding tube; a piston-type slide valvepositioned to selectively open or close the withdrawal openings; whereinthe feeding tube extends into the proximity of the bottom of the drumand is adjustable in an axial direction, and wherein a connection piecefor the connection of a suction device is arranged below the shut-offelement, the bottom of the centrifugal drum having a gradient toward thecenter in which the feeding tube is arranged.
 4. The separator accordingto claim 3, further comprising a shutoff valve arranged in theconnection piece leading to the suction device.
 5. The separatoraccording to claim 3, further comprising an adjusting device for axialadjustment of the feeding tube.